"Senior investigator says probable crash site hundreds of miles south of area of fruitless underwater search that lasted months"

Now search efforts are moving south, hundreds of miles from where authorities initial believed the plane went down on March 8, ABC News reports.

The chief commissioner of the Australian Transport Safety Bureau, Martin Dolan, told reporters that an announcement will be made next week about where the search will be focused. The new search site covers about 23,000 square miles and will use powerful state-of-the-art sonar equipment.

Dolan told the AP that he thought the probable crash site would be hundreds of miles south of where the previous searches have been. One of the main pieces of equipment involved in the search is an underwater drone. It had searched 330 square miles last month alone.

At first, searchers had hope that acoustic signals were coming from the missing plane’s black box. But now they believe those signals were coming from another source, not Malaysia Airlines Flight 370. It is not clear what could have generated those weak signals that gave searchers a false hope.

The BBC's Jonathan Amos, reports, "The new search area(s) that the ATSB promise to announce shortly must be tied to the ocean-bed mapping now being conducted by survey ships. Their information is critical to guiding underwater sweeps. Without proper depth data, you cannot choose the most appropriate submersibles to look for MH370 wreckage.

"The Australian authorities tell me that the Dutch-owned Fugro Equator is currently working in an area located along the arc where Inmarsat made a seventh and final connection with the lost jet."

Authorities say that the planed new southern search area is based on refining analysis of satellite information from the lost plane. The Malaysian plane, a Boeing 777, inexplicably went off course during a flight from Kuala Lumpur to Beijing on March 8.

"All the trends of this analysis will move the search area south of where it was," Dolan said. "Just how much south is something that we're still working on."

"There was a very complex analysis and there were several different ways of looking at it. Specialists have used several different methodologies and bringing all of that work together to get a consensus view is what we're finalizing at the moment," he added.

The new search will be conducted by private contractors and it won’t be done quickly. It is expected to take as long as a year.

When MH370 went down with 239 passengers and crew. No debris has ever been found.

The new search area will stretch as far southwest as off the Australian city of Perth.

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